Recently, the semiconductor devices to be used in information devices, electronic devices, etc. are required to increase the operational speeds and to decrease the power consumptions, etc.
To realize the increase of the operational speed, it is proposed to use copper (Cu) as the material of the interconnections of the multilayer interconnection structure to be formed on an inter-layer insulation film. The use of Cu as the material of the interconnections can decrease the electric resistance of the interconnections, and can contribute to the increase of the operational speed, etc.
Related reference is International Publication Pamphlet No. WO 2007/026429.